Generally, mobile devices, display devices, semiconductor devices, and switching devices, etc. include a plurality of thin film patterns, and the thin film patterns are formed by a photolithography process and an etching process.
A thin film pattern array includes a lower thin film pattern formed on a substrate and an insulating layer formed on the lower thin film pattern using a deposition method, etc. such as plasma-enhanced chemical vapor deposition (PE-CVD). An upper thin film pattern which is electrically insulated from the lower thin film pattern is formed on the insulating layer. The lower and upper thin film patterns are formed by the photolithography process and the etching process. Here, an end portion of each of the thin film patterns has a nearly vertical taper angle. As a result, the insulating layer formed around the end portion of each of the thin film patterns also has the nearly vertical taper angle close. When forming the upper thin film pattern on the structure described above, the width of the upper thin film pattern becomes thin or the upper thin film pattern is cut where a step difference is generated. When the width of the thin film pattern becomes too thin, resistance becomes locally increased, and heating occurs which causes complications. Further, if the upper thin film pattern is cut another complication can occur when the electrical signal becomes abnormally transmitted. Additionally, when the insulating layer is cut, a short-circuit complication occurs due to the lower thin film pattern and the upper thin film pattern coming into contact with each other.
In order to solve these complications, various conventional methods have been proposed. First, a method of forming the taper angle by controlling the material property, composition ratio, temperature, etc. of an etchant (or gas) has been proposed. However, it is difficult to form a specific taper angle since the method is sensitive to changes of a material, a deposition method, a thickness, etc. of the thin film.
Next, a method using an adhesion property of a thin film and photoresist has been proposed. However, it is difficult to perform a normal process due to a low adhesion property of the photoresist.